Salicornia and other annuals colonising mud and sand is a community of pioneer saltmarsh plants that colonises intertidal mud and sandflats in areas protected from strong wave action. This pioneer saltmarsh is an important precursor to the development of more stable saltmarsh vegetation. Salicornia and other annuals colonising mud and sand develops at the lower reaches of the saltmarsh where the plants are frequently flooded by the tide. It can also colonise open creek sides, depressions or pans within saltmarshes, as well as disturbed areas of upper saltmarsh.

The Salicornia feature in Carmarthen Bay and Estuaries SAC includes Salicornia from the Burry Inlet, Loughor and the Three Rivers estuaries. The baseline extent of Salicornia in Carmarthen Bay and Estuaries SAC has been measured as 34.14 ha (2003). However, the current extent of Salicornia cannot be calculated as there is no up to date mapping. 

The Salicornia feature is pioneer saltmarsh that develops on intertidal mud and sandflats in areas protected from strong wave action and where the elevation is high enough to enable colonisation by annual plants. The majority of this feature is dominated by Glassworts Salicornia sp. however, stands of pioneer marsh can also be dominated by Annual Sea-blite Suaeda maritima which is much less common.

The Salicornia feature is relatively scarce in the Burry Inlet but well represented on the Landimore to Llanrhidian marshes, where sizeable stands form good sequences between pioneer marsh and Atlantic salt meadows. These communities are scarce within the Three Rivers complex with small but representative stands of Salicornia existing on both the Taf and the Gwendraeth.